About cookies on this site Our websites require some cookies to function properly (required). In addition, other cookies may be used with your consent to analyze site usage, improve the user experience and for advertising. For more information, please review your options. By visiting our website, you agree to our processing of information as described in IBM’sprivacy statement. To provide a smooth navigation, your cookie preferences will be shared across the IBM web domains listed here.
Paper
Magnetization transfer in cross‐linked bovine serum albumin solutions at 200 MHz: A model for tissue
Abstract
We report results for proton 1/T1, 1/T2, and K, the rate of magnetization transfer from solvent to solute, for 5 and 10 wt. % solutions of bovine serum albumin, both native and chemically cross‐linked, in undeuterated and ∼50% deuterated water, at 4.7 T (200.1 MHz) and 19°C. At this field, although K > 1/T1 for the cross‐linked samples, magnetization transfer contributes little to 1/T1 directly. Therefore K was measured using off‐resonance irradiation of the protein protons. The data for all the samples can be fit using a theoretical model for magnetization transfer, with three parameters: the intrinsic longitudinal relaxation rates of solute and solvent protons, and K. The magnitude of Kis so large that the newly‐identified, long‐lived (∼1 μs) hydration sites (S. H. Koenig, R. D. Brown III, and R. Ugolini, Magn. Reson. Med., 29, 77 (1993)) must be invoked to account for K, as is necessary to explain the differential effects of cross linking on the magnetic field dependence of 1/T1 of protons and deuterons and the large 1/T1 and 1/T2 values below ∼20 MHz in immobilized systems. Although these sites are few in number, their long resident lifetime becomes the correlation time for magnetization transfer when protein is immobilized, accounting for the large value of K. Recent data from several laboratories have shown that cross‐linked protein, as used here, is a good model for 1/T1 and 1/T2 of tissue, as a function of temperature and magnetic field. Copyright © 1993 Wiley‐Liss, Inc., A Wiley Company